1. Field
Embodiments of the present invention relate generally to an organic light emitting display device and driving methods therefor. More particularly, embodiments of the present invention relate to an organic light emitting display device capable of compensating for a degradation of an organic light emitting diode (OLED), and driving methods therefor.
2. Description of the Related Art
As information technology has developed, the importance of display devices as connection media between users and information has emerged. In line with this, the use of display devices such as liquid crystal display devices, organic light emitting display devices, and plasma display panels (PDPs) has increased.
Among display devices, an organic light emitting display device displays an image using an OLED generating light according to hole-electron recombination, which advantageously has a fast response speed and is driven at low power consumption.
The organic light emitting display device includes a plurality of pixels positioned in regions divided by a plurality of data lines and scan lines. Each of the pixels generally includes an OLED, two or more transistors including a driving transistor, and one or more capacitors.
The OLED included in each of the pixels has been found to degrade with the passage of time, and in particular, image brightness decreases over time. Thus, a method for compensating for this degradation of the OLED is required.
Meanwhile, the driving transistor included in each of the pixels is driven in its saturation region. When the driving transistor is driven in the saturation region, ideally, current should be uniformly maintained regardless of change in a voltage (hereinafter, referred to as a “Vds”) between a drain electrode and a source electrode. However, current actually varies according to a change in the voltage Vds, due to channel length modulation of the driving transistor. Thus, a method for compensating for degradation of the OLED may take into account channel length modulation of the driving transistor.